The ratio is defined to the maximum brightness value (white) divided by the minimum brightness value (black) ratio. The ratio of the CRT monitor is usually up to 500: 1 led display production tutorial that presents a real all-black screen on CRT monitor is very easy. But LCD is not very easy, backlight cold cathode ray tube is composed of hard to do fast switching operation, so the backlight is always in the lit state. In order to get a black screen indoor led display, LCD modules must be completely light coming from the backlight completely blocked, but in the physical characteristics of these components and can not fully meet this requirement, we will always be some light leakage occurs. In general, the ratio of the human eye can accept about 250: 1. Against Heat: CRT monitors as big heat, the heat will shorten the life of the display, other components will be accelerated aging, it CRT monitor placed in a ventilated environment a better place, it is best to place the monitor in an air-conditioned room in, or a wind blowing fan led display, to extend the life of the display. Against Heat: CRT monitors as big heat full color led display, high temperatures will shorten the life of the display, other components will be accelerated aging, it CRT monitor placed in a ventilated environment a better place, it is best to place the monitor In the air-conditioned room, or a wind blowing fan to extend the life of the display. led screen repair _ 金锐光 electricity (certified) _ Yidu led display provided by Yichang Technology Co. 金锐光. Yichang Jinrui Guang Technology Co., Ltd. (www.ycjrgd.com/) Hubei Yichang, Electronics & Electrical Project Cooperation leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs . In Jinrui Guang electric leadership with the staff warmly welcome all inquiries negotiations to create a better future Jinrui Guang electricity.